Conventionally, hot-melt adhesives have been widely used because those are excellent from environmental viewpoints and for their convenience.
As a base polymer for the hot-melt adhesives, vinyl aromatic hydrocarbon-conjugated diene based block copolymers (SBS) are known for their high versatility.
Also in the related art, an adhesive composition using the block copolymer has been disclosed (for example, see Patent Literatures 1 and 2.). Generally, however, the SBS has poor thermal stability, and the adhesive composition using this is likely to be less balanced between retentivity and tackiness, and have high melt viscosity and insufficient processability. For this reason, an adhesive composition composed of a triblock copolymer and a diblock copolymer has been proposed as an improved technique for these (for example, see Patent Document 3 and Non Patent Document 1.).
Moreover, an adhesive composition composed of a block copolymer obtained by performing coupling with a specific bifunctional coupling agent (an aliphatic monoester, a specific dihalogen compound) has been proposed (for example, see Patent Document 4.).
Further, a composition containing a block copolymer obtained by hydrogenating a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene based compound and a tackifier has been proposed as further improvement of these related arts (for example, see Patent Document 5.).    Patent Document 1: Japanese Patent Publication No. 44-17037    Patent Document 2: Japanese Patent Publication No. 56-49958    Patent Document 3: Japanese Patent Application Laid-Open No. 61-278578    Patent Document 4: Japanese Patent Application Laid-Open No. 61-261310    Patent Document 5: Japanese Patent Publication No. 05-69874    Non Patent Document 1: “Secchaku (Adhesion)” (vol. 32, No. 1, p. 27 ('88))